Asalaamu Alaikum, KFC chicken is very doubtful as they open and honestly claim to yse "stunning methods" to slaughter chickens and HFA accept these methods but the overwhelming majoriy of scholars do not accept that "Stunning methods" use to slaughter chickens conform with Islamic Slaughter criterea.
I myself have spoken to HFA on a number of occassions and they do not have scholarly backing for their certification nor do they ever monitor the takeaway or restaurant they are certifying. So how can they blindly certify a place halal when they never do any checks on them? Whereas HMC actively monitor randomly any place that they certify and have strict guidelines to ensure any place they are certifying meets Islamic slaughter critierea laid down by scholars.
So therefore it is best to keep away from any butchers, takeaway or restaurant serving chicken which has been slaughtered by "stunning".
Asalaamu ALaikum, jazakallah for your enquiry sister. You can find halal restaurants, takeaways and butchers across the country in the following link which is of an organisation called HMC who actively monitor and rigorously check all the places they certify unlike any other "halal cerfification" organisation. So it gives one peace of mind that one is truly eating halal.
If you do have any further questions or need any advice on any matter at all then please do not hesitate to ask.